Your amazing toddler: "Wow!"-worthy development facts

There's so much for your go-go-go toddler to learn! A toddler's buzzing brain soaks up new information like a sponge, which can make it hard to sit still or go to sleep. Here are three fascinating facts about your toddler’s development that you might not know.

Learning to talk

Children understand language much earlier than they can speak it. By age 1, they typically understand about 70 words but speak only a handful of them, says neuroscientist Lise Eliot, an associate professor of neuroscience at Chicago Medical School and author of What's Going On in There? How the Brain and Mind Develop in the First Five Years of Life.

At about 18 months, toddlers' spoken vocabulary starts to explode. They add new words at the astonishing rate of one every two waking hours.

By age 6, they typically understand about 13,000 words (compared with your 60,000 or so), although they're not likely to speak that many.

Right-handed or left-handed?

Most 1-year-olds are ambidextrous (they use both hands equally). Your toddler will probably start showing a preference for the right or left hand by age 2 or 3 — and in about 90 percent of kids, it'll be the right.

Why so many righties? No one knows for sure, says neuroscientist Eliot. Genetics plays a role (southpaw parents are more likely to have kids who are also lefties), as do social norms. There are more lefties in the United States than in cultures in which left-handedness is considered unacceptable.

There's also a theory that says more people are right-handed because three-quarters of babies in utero spend the last weeks of gestation with their right arm facing out, allowing it to move more freely. Another says that it's because newborns are more likely to turn their heads to the right than to the left (though the reasons for this are unclear). Yet another says it's simply a learned behavior — you hand things to your child with your right hand, and he follows suit.

Brain gain

Basic brain functions are already in place at birth. But the cerebral cortex — the part of the brain that has thoughts, stores memories, and controls voluntary muscle movement — only kicks into gear after encountering the world outside the womb.

Between ages 1 and 2, the cerebral cortex adds more than 2 million new synapses — the connections between brain cells — every second, according to Zero to Three, a nonprofit educational group. By age 2, toddlers have more than 100 trillion synapses, the most they'll ever have in their life. That's part of the reason they have such an incredible capacity to learn.

This period of "synaptic exuberance" can last until age 8, but it's also accompanied by the constant pruning of unused synapses. By the time your child reaches adulthood, more than 50 percent of those neural pathways will be gone.

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Dan Tynan writes about parenting and technology for a wide range of publications and in his blog,Tynan Writes. Christina Wood is a magazine writer and author of Every Woman's Guide to Technology. She blogs atGeek Girlfriends.

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